People are generally aware of the most common causes of hallucinations, like schizophrenia and a really high fever. But lesser known are the more rare causes; here are six you probably haven't heard about.

Even local, non-metastatic prostate cancer can be a moving target, according to a new study. Researchers from the University of California Los Angeles (UCLA) have discovered that prostate tumors can evade treatment by evolving a set of different cancer-driving stem cells. The cancer growth thus becomes an ever-changing process that problematizes targeted therapies. According to the authors, the findings will help oncologists and scientist develop new treatment strategies that focus on the tumor’s evolving properties.

In many cases of prostate cancer, the tumor growth is sustained by a type of stem cells called basal stem cells. However, as the cancer matures, the task of sustaining the growth can be shifted over to a different type of stem cells called luminal-like tumor stem cells. For this reason, targeted treatments can fail to induce relevant cell death, as the cancer’s proliferative capacity is suddenly refracted through a range of cell groups. It won’t sit still, in other words.

"People have begun to think about cancers as being driven by stem cells in the same way that many of our adult organs are maintained by dedicated stem cells," senior author Andrew Goldstein said, referring to the process whereby stem cells assume different cellular properties to fit the need of a particular organ. "Based on this new understanding, a lot of excitement surrounds the concept of going right to the root of the tumor and targeting those stem cells to eradicate the cancer."

Goldstein and his colleagues hope that their discovery will help oncologists anticipate and subsequently suppress this type of “fluid” tumor growth. The next step is to perform a more thorough analysis of the stem cells themselves.

The current study dovetails with a number of inquiries into targeted and personalized cancer therapies. In another study published earlier this year, researchers from The Institute of Cancer Research in London showed that analyses of a single cancer cell can yield a “family tree” of the tumor’s genetic diversity. By broadening the current understanding of a tumor’s genetic and evolutionary profile, these two studies may come to have a tremendous impact on oncological diagnosis and treatment.